The patents EP 1 055 877 B1 and EP 1 590 408 B1 by the same applicant describe soot generators that are capable of generating soot particles having well-defined chemical and physical properties. To this end, fuel and oxidizing gas are fed into a combustion chamber in such a way as to form a diffusion flame, which creates soot particles. The tip of the diffusion flame is exposed to the oncoming flow of a quenching gas, so that the combustion process is stopped and the soot particles are carried away. These soot generators have proven to be particularly successful when used with gaseous fuels. It has been found that liquid fuels are less suitable for generating soot particles having the desired properties.